In a cell for ion exchange membrane electrolysis used for chlorine-alkaline electrolysis, three components of the cell for ion exchange membrane electrolysis, which are an anode, an ion exchange membrane and a hydrogen-generating cathode, are normally arranged in close contact with each other to promote reduction in electrolysis voltage. However, in a large-scale cell which attains as much as several square meters of electrolysis area, when an anode and a cathode made of a rigid member were accommodated in the cell, it was difficult to maintain the distance between the electrodes at a determined value, with both electrodes brought into close contact with an ion exchange membrane.
A cell is known in which an elastic material is employed on an item used as a means to reduce the distance between electrodes or between an electrode and a current collector or as a means to maintain the distance between them at a nearly constant value. Such a cell has a structure in which at least one of the electrodes moves freely in the direction from one electrode to the other in order to avoid breakage of an ion exchange membrane by uniformly close contact of the electrode with the ion exchange membrane and to maintain the minimum distance between the anode and the cathode, and the pinch pressure is controlled by pressing the electrode through the elastic member. Non-rigid materials such as woven fabric, non-woven fabric, mesh and the like, which are formed of a metal fine wire; and rigid materials such as leaf spring and the like are known as examples of this elastic material.
However, conventional non-rigid materials had disadvantages. For example, when excessive pressure is applied to a conventional non-rigid material from the anode side after attaching it to a cell, the non-rigid material is partially deformed to have a non-uniform distance between electrodes and/or an ion exchange membrane is pricked with a fine wire of the non-rigid material. Moreover, rigid materials such as leaf spring and the like had disadvantages. For example, a rigid material damages an ion exchange membrane and/or causes plastic deformation of an ion exchange membrane so that the ion exchange membrane cannot be reused. Furthermore, for a cell for ion exchange membrane electrolysis such as a brine cell, the close proximity of an anode and/or a cathode to an ion exchange membrane is preferred to allow continuous operation of the cell at a low voltage and therefore various methods to press an electrode toward an ion exchange membrane are proposed.
For example, Patent Document 1 proposes a cell in which a metal coil body instead of a conventionally used leaf spring or metal mesh body is attached between a cathode and a cathode end plate and the cathode is uniformly pressed toward a barrier membrane to bring each member into close contact with the barrier membrane. Moreover, Patent Document 2 proposes a cell for ion exchange membrane electrolysis improved upon the technology of Patent Document 1, in which an elastic cushion member is attached between a hydrogen-generating cathode and a current collecting plate on the cathode side and the hydrogen-generating cathode is uniformly pressed toward an ion exchange membrane, wherein this elastic cushion member is prepared by winding a metal coil body around a corrosion-resistant frame.